Engine synchronization means



1952 P. F. BECHBERGER ETAL ,6

ENGINE SYNCHRONIZATION MEKNS 2 SHEETS-Sl-IEET 1 Filed July 15, 1947 INVENTORS PHUL E BEL'HBEHEEH JUEL D. PETERSEN 2 SHEETS--SHEET 2 INVENTORJ PHUL E BEL'HBEREER JUEL l1 PETERSEN fl7T'OR/VE) P F BECHBERGER ETAL ENGINE SYNCHRONIZATION MEANS Oct. 21, 1952 Filed July 15, 1947 Patented Oct. 21, 1952 ENGINE SYNCHRONIZATION MEANS Paul F. Bechberger, Tenafly, and Joel D. Peterson, Ridgewood, N. J., assignors to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware ApplicationJuly 15, 1947, Serial No. 760,950

- This invention relates to anengine speed control and synchronizing system, and more par- ,ticularly to an engine control and synchronizing system for aircraft engines wherein signal voltages control the engine speed.

An objector" the present invention is to provide a speed control andsynchronizing system for a plurality of engines whereby the speed of the engines may be controlled at will from a remote point, and the speeds of the engines synchronized with that of one of the engines designated as the master enginewithout the use of complicated lever,-pulley or flexible shafting assemblies. v 7

Another object of our invention is to provide aspeed control and synchronizing system fora plurality of engines in which signal voltages are developed for controlling the speeds of the engines, and in which signal voltages are developed responsive to enginespeeds to control the syn chronization of the engines.

A further object of the invention is to provide a speed control 'andsynchronizing system for engines of .the character indicated in which signal voltages responsive to the difference in the speeds of the engines vary the controlling signal voltages for the slave engines to synchronize the speeds thereof with that of the master engine.

, Still another object of this invention is to provide a speed control and synchronizing system for engines of the character described which is independent oi thefiuctuations in the amplitude, or in the frequency of the source of voltage, and which is independent of the'variations or characteristics of the engines controlled, or their speed controlling devices.

8Claims. (01.60-97) v Fig. l is a schematic wiring diagram illustrating our system .as used in varying the bias of a speeder spring of a propeller pitch governor unit, while" Fig. 2 is a schematic wiring diagram similar to Fig.1 illustrating another embodiment of our invention. f I" 'l 1..

. Referring now in detail to Fig. l of the drawings, thenum'eral. lflfdesi'gnates a circuit interconnecting a c ont'rollever [I with the propeller governors l2 and i3 controlling the pitch of propellers l6 and ifi'of'the aircraft engines lfi'and ll, respectively. The engineIB [will be herein after referred to as the master engine while engine I! will be referred to as the slave engine, the speed ofpwhich is to be synchronized with that of engine IS.

The circuit It) comprises a synchronous generator or transmitterlB, having a rotorwin'ding l9 and a stator winding 20. The rotor winding :9 is connected across a suitable source; of potential 2i and is adapted to be angularly displaced by movement of the control lever H 1 through suitable gearing indicated .by the dashed ,Yet another object of our invention is to provide a speed control and synchronizing system for engines of the characterdescribed which shall'besimple to operate with respect to the control of engine speed and automatic with respect to engine synchronization; relatively inexpensive to manufacture, whichshall have a large variety of applications; and yet be practical and efiicient to a high degree in use.

Other objects of the present invention will in part be obvious and in part hereinafter pointed out.

In the accompanying drawings forming a part of this specification in which two of the various possible illustrative embodiments of this inline 22.

gine l6.

The three phase stator winding '20 is conne'ctedbyleads 23 to the three phase stator winding 24 of asynchro or receiver 25. Thereceiver 25 also comprises a single phase; rotor winding 26 adapted to be rotated by a two phase induction motor-'2! as by gearing 28. The transmitter l8,the receiver 25 and the two phase motor 2? control the speed of the master en- Control of the slave engine is accomplished by similar units in the circuit I0, and comprisinga second synchronous generator or transmitter 29 similar to transmitter I8, having a rotor 30 connected across the source of potential 2| and adapted to be rotated through gearing 3i bythe lever H and a receiver 35. The transmitter 29 is provided with a three phase stator winding "32 connected asby leads 33 to the three phase stator winding of the receiver 35. The receiver 35 is provided with a single phase rotor 36 adaptedto be rotated by a two phase induction motor 31, as by gearing 38. As will hereinafter, appearthe stator winding 32 of the trans- ,mitter 29 is adapted to be angularly displaced by the operation of a gear train, or other coupling devices, shown on the drawings by the dashed line 39. I

The receiver rotors 26 and 36 are connected by suitable leads 40 to the input side of amplifiers 4|; the output of said amplifiers being connected to the variable phases 42 and 43 of the two phase 7 will appear in the stator windings 24 and 34 of the receivers 25 and 35, respectively. The voltage appearing in the stator windings of the receivers will in turn induce a. voltage in their associated rotor windings 26 and 36 which, when amplified, is applied to the Variable phases of the two phase motors 21 and 31. The voltage appearing in the variable phases 42 and 43 will cause the respective induction motors to operate to position the receiver rotors 26 and 36' to a null position. at which no voltage is induced in the rotor windings. With no voltage being applied to the amplifiers at, the two induction motors 21 and 31 will be brought to a standstill.

The electricalcircuit H) is provided with means for varying the speed' setting of the propeller governors I2 and |3. To this end, there is provided for each of the two phase induction motors 2'! and 31a gear train, herein indicated by the dashed line 46 and 47, terminating in pinions 48' and 49,'respective1y'. The pinion 48 is adapted to mesh with a rack 50 of: the propeller governor l2, which pinion 49'meshes with a rack 5| of the propeller governor |3.

, The'propeller governors l2 and I3 are of the type well, known in the art, and comprise a speeder spring 52 fixed at its. upper end to the lower end of rack 56 (or 5|) andatits lower end to a disc 5Tfixedto the upper end of a rod' 53. The. rod 53 is iournalled in a sleeve 54 adapted to. be rotated by the aircraft engine l6 (or l1).

The enlarged portion 55 of the sleeve 54 has pivoted thereto weighted bellcrank members 56 adapted. to. coact with the disc 5'! on the upper end of the rod 53.

In response to the speed of the engine the weighted bellcrank members 56 will fly outwardly,

tending to lift the disc ST and the rod 53 against the bias of the spring 52. Movement of the rod 53. by the weighted members will vary the propeller pitchin the manner well known in the art.

Upon operation of the two phase motors 21 and 3'! to position the transmitter rotors 26*and 36 to; a new null position as demanded by the angular. displacement ,of the rotors of their respective transmitters, the speeder spring bias of the. propeller governors l2 and. I3 will be varied by the rotation of the. pinions 48 and 49 moving the racks 59- and 5|. The movement of the racks will either increase or decrease the bias of the Speeder. springs, thus affecting the response of the weightedmembers to the engine speeds. The pitch of the propellers. l4 and I5 are thus varied in. accordance with the position of the control lever ll.

Means is now provided to match the speed of the engine H with that of the master engine l6.

To this end there are provided synchronous transmitters or'generators 60 and 6| having single phase rotors 62' and 63, respectively, connected across the source of potential 2| and adapted to be rotated by the engine shafts as indicated by the dashed lines 64 and 65; respectively. The three phase stator winding 66- of the transmitterfifl is connected by suitable leads 61' to a three phase stator winding 68 of a differential motor 69, while the three phase winding 10 of the transmitter 6| is connected by leads H to the three phase rotor winding 12 of the differential motor 69. The differential rotor 12 is coupled by the gear train 39 hereinbefore described, to the stator winding 32 of the transmitter 29.

Rotation of the rotors 62 and 63 by their respective engines will induce in the respective stator windings 66 and 10 a voltage which gives rise to a rotating magnetic field in the stator and rotor windings of the diiierential motor 69 to which said transmitter stators are connected. When the speeds. of the engines l6 and H are the same the two rotating magnetic fieIds in the difierential motor 69 will rotate at the same speed. No rotation of the rotor winding 12 will take place under this condition.

When a difference in engine speed exists between the engines IB and H, the speed of the rotating field in the rotor 68 will be different than that of therotating field in the rotor winding 12. The reaction of the two rotating magnetic fields will cause the rotor 1-2 to be angularly displaced in accordance with the difference in engine speeds. The angular displacement of the rotor 12 will cause an angular displacement of the stator winding 32' of the transmitter 29. A change in the relative positions of the rotor 30 and stator 32 will change the signal voltage induced in the stator. The change in signal voltage is impressed on the rotor 36, amplified and applied to the variable phase of the two phase motor 37. The motor 31 will thus rotate to displace the rotor 36 to a new null position and to reposition the rack 5| in the manner hereinbefore described. The bias of the Speeder sprin 52 is thus altered; changing the pitch ofpropeller l5 to bring the speed of the engine IT in synchronism with that of'engine l6.

Referring now to Fig. 2' of the drawings, in which a" second embodiment of' our invention is illustrated, the control circuit for the slave engine l1 includes therein a" source of variable voltage responsive to the speed difference between the slave and master-engines.

The control circuit for the slave engine H comprises synchronous motor-8'3 having a three phase stator winding SI and a single phase rotor winding 82'. The rotor82' is adapted to be angularly displaced with respect to the stator coil 8| by means of the control lever through a gearing, or other coupling indicated by the dashed line 83. The motor as is connected by suitable leads 84'. to' a synchro transmitter 35 having a three phase stator winding, 86 and a single phase rotor. winding. 8T; the three phase stator winding 8| being connected to the three phase stator winding 66. The single phase winding 81' is connected across the source of potential 2| and is adapted to be rotated by the induction motor 3 through suitable gearing The single phase winding is connected by leads 89' to the input of the amplifier 4|. controlling the variable phase 43 of the induction motor 31'. When. the rotors 82' and 81' are in positional agreement, no voltage will be induced in the rotor winding 82. The variable phase 43 of the induction motor will be d'e-energized and no angulardisplacement o'fthe rotor winding 87 will take-place;

When the control handle H is moved, the magnetic balance heretofore had will be dis".- turbed, causing a voltage to" be induced in the amplifier] and applied to the variable phase '43. t The induction motor 31 is thus operated to displace the rotor .81 into positional agreement with, that of the rotor 32. Rotation of the motor 31 will vary the bias of the speeder spring 52 of-the propeller governor 13 through the gear train 4'! and pinion hereinbefore described. M Y

The circuit for the control of the speeder spring 52 for the master engine I6 is the same 49 in the manner as that described inconnection with Fig; l.

Means'is now provided to induce in series with the positional signal voltage of the rotor "82 a signal voltage in proportion to the speed difference of the two engines.

To this end,-a rotary transformer 90 is provided having a rotor coil 9| connected across the source of' potential 2] and movable with suitable coupling or gearing 93'.

When the two engines It and if "are in agreement as to their respective speeds, the rotating magnetic ii'elds in the stator and rotor windings of the diiferentialmotonfii! impressed thereon by the generators 6| and Eli, respectively, cancel one another and no rotation of the rotor 12 will take place. "A difference in speeds of the two magnetic fields will, due to the magnetic reaction" of the two fields, cause an angular displacement of .the. rotor 12. Through the gearing 93, the rotor 12 will. angularly displace the rotor 9| of the rotary transformer 98 to induce a voltage in the stator winding 92. This change in the induced voltage will be in proportion to the difference in speed of the two engines and is added in series with the signal volt age of that of the rotor 82. The induction .motor 3'! is operated to displace the rotor 81 for 'It will be'a'ppr'eciated thatithe speed control an'd'synchronizing systems hereinabove described are independent of fluctuations either in the amplitude or in the frequency of the voltage source 21 since the system depends upon its operation on magnetically balanced circuits. Since all of the induction devices are connected to the same source of supply any changes taking place therein, take place equally throughout the entire system. Variations in the calibration of the speeder springs 52 and/or in the characteristics of the fly ball members 56 are automatically compensated for in synchronizing the engine speeds in that the speed of the engines govern the magnetic balance of the circuits. The circuits will bias the Speeder springs more or less as needed for any particular required engine speed.

It will thus be seen that there is provided a control and synchronizing system in which the several objects of this invention are achieved and which is well adapted to meet the conditions of practical use.

As various possible embodiments may be made of the invention above set forth, and as various 6 changes might be made in the two embodiments set forth above, it is to be understood that all matter herein described, or illustrated in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, we claim as new and desire to secure by Letters Patent:

1. In speed control and synchronizing systems for engines, one of said engines acting as a master or reference engine, the combination with speed regulating means for each engine, of motive means for actuating said speed regulating means, a displaceable control lever, inductive means coupled to said control lever adapted to develop signal voltages responsive to the displacement of said lever, means responsive to said signal voltages to operate said motive means; and differential means for varying the initial signal voltages in response to the differences in the engine speeds to vary the actuation of the speed regulating means associated with each engine except that of the reference enginefto synchronize the engine speeds to that of the reference engine.

2. In speed control and synchronizing systems for engines, one of said engines acting as a master or reference engine, the combination with speed regulating means for each engine, of motive means for actuating said speed regulating means, a displaceable control lever, inductive means coupled to said lever and adapted to develop signal voltages responsive to the displacement thereof, means responsive to said signal voltages to operate said motive means, means for developing a signal responsive to the speed of each engine; and differential means for varying the initial signal voltages except that of the reference engine in response to differences in the speed signals to vary the operation of the motive means to synchronize the engine speeds to that of the referenceengine.

In speed control and synchronizing systems for engines, one of said engine's acting as master or reference engine, the combination with speed regulating means for each engine, of motive means for actuating said speed regulating means, a displaceable control'lever, a circuit for controlling said motive means includingan inductive device for each engine coupled to said lever and adapted to develop. signal voltagesresponsive to. the displacement thereof for operatingsaid motive means, inductive devices coupled to said motive means for cancelling said signal voltages when the engine speed is in agreement with lever displacement; and means for varying the signal voltages of said inductive devices, except that for the reference engine, in response to the differences in engine speeds to synchronize the speeds with that of the reference engine.

4. A speed control and synchronizing system for engines, one of said engines acting as the master or reference engine, comprising a propeller governor for each of said engines including a speeder spring and fly ball members, a servomotor for each governor adapted to vary the bias of said speeder spring to aifect the response of said fly ball members to engine speed, a control lever, an inductive device for each servomotor coupled to said lever and adapted to develop signal voltages in response to the movement thereof for operating said servomotor, inductive devices connected to each of said first devices and driven by said servomotors for nullifying the signal voltages of said first devices when the speeds of said engines arein agreement with the position of said lever, means drivenby each engine for developing a signal in response to the speed thereof, induction means connected to said driven means and responsive to the speed signals and modifying the initial signal voltages, except that of the reference engine, to synchronize the engine speeds with that of the reference engine.

5. A speed control and synchronizing system for two engines, one of said engines acting as the master engine, comprising a propeller governor for each of said engines including a speeder spring and fly ball members, a servomotor for each governor adapted to vary the bias of said :speeder spring to affect the response-of said fly ball members to engine speed, a control lever,,an

inductive device for each servomotor coupled to said lever and adapted to develop signal voltages ,in response to the movement thereof for operating said servomotor, inductive devices connected to each of said first devices and driven by said servomotors for nullifying the signal voltages of said first devices when the speed of said engines are in agreement with the position of said lever, means driven by each engine developing a signal in response to the speed thereof, a differential .motor having a stator and a rotor each connected to one of said signal means, a rotary transformer having a stator and a rotor, said rotor being driven by said differential rotor, the transformer stator being connected in series with the induction device of the slave engine, the changes in voltage induced in the transformer stator modifying the initial signal voltage to bring the slave engine into synchronism with the master engine.

6. A speed control and synchronizing system for two engines, one of said engines acting as the master engine, comprising a propeller governor for each of said engines including a speeder spring and fly ball members, a servomotor for each governor adapted to vary the bias of said speeder spring to affect the response of said fly ball members to engine speed, a control lever, an inductive device for each servomotor coupled to said lever and adapted .to develop signal voltages in response to the movement thereof for operating said servomotor, inductive devices connected to each of said first devices and driven by said servomotors for nullifying the signal voltages of said .flrst devices when the speed of said engines are in agreement with the position of said .lever, means driven by each engine developing a signal .in .response to the speed thereof, a differential motor having a stator and a rotor each connected to one of said engine driven signal means, and means coupling said differential rotor to the slave engine induction device to alter the signal voltages developed thereby for synchronizing the speeds of the slave engine to that of the master engine.

7. A speed control and synchronizing system for a plurality of engines having speed regulating means, one of said engines serving as a master engine; comprising means for developing a signal voltage in accordance with a desired engine speed, motive means actuating .each of the speed regulating means responsive to said signal voltages, means driven by the engines to develop signals responsive to engine speeds, and difierential means responsive to thespeed signals and operative upon differences in the speeds of said engines to vary the initial signal voltages controlling the slave motive means for synchronizing the speeds of the engines.

8. A control system for two engines comprising a differential motor having a stator and a rotor, an induction device for each engine and driven thereby, connected to said differential rotor and stator respectively and developing a rotating magnetic field therein, a difference in thespeeds of the rotating fields displacing said differential rotor; induction means for developing .a signal voltage in accordance with desired engine speed, speed regulating means for each engine responsive to said signal voltages, and means operable upon displacement of said differential rotor to vary the signal voltages to one of said speed regulating means to synchronize engine speeds.

PAUL F. BECHBERGER. .JOEL D. PETERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,562,917 Richter Nov. 24, 1925 2,205,265 Kalin June 18, 1940 2,412,605 Drake Dec. 17, 1946 

